The effect of rHuEPO on arterial blood pressure has been demonstrated to occur independent of its haematopoietic effect and subsequent effect on blood viscosity. Recently, we reported that also short-time administration of very high doses of rHuEPO (30,000 IU/day for three days) increases arterial blood pressure and the blood pressure response to exercise to a similar extent as prolonged, low-dose rHuEPO for three month. The exact mechanisms remains unclear, but may involve rHuEPO induced release of endothelin and inhibition of eNOS mediated production of NO.